1. Field of the Invention
The present invention relates to solar cells, and in particular to solar cells having a ribbed structure on a radiation-receiving surface thereof.
2. Description of the Prior Art
A solar cell having a ribbed and/or honeycomb structure on a radiation-receiving surface thereof and a pn-junction below the ribbed surface which follows the contour of that surface, in contrast to solar cells with a plane surface and a pn-junction disposed in a plane parallel to the surface and perpendicular to the incident solar radiation, has been proposed in Hovel, "Solar Cells", pages 139 ff., Vol. 11 of Semiconductors and Semimetals, Academic Press, 1975. The ribs or honeycombs extend parallel to the incident solar radiation into the semiconductor body.
In an attempt to make such a solar cell insensitive to the destructive influence of cosmic radiation and the like, and in order to employ such a solar cell over the long periods of time necessary for, for example, space experiments, a semiconductor structure has been disclosed in Conference Record, 14th IEEE Photovoltaic Specialists Conf. (1980), pp. 151-155, which has the appearance in cross section of a comb with broad teeth and interstices between the teeth which are very narrow in comparison with the width of the teeth. The interstices are manufactured by etching a single crystal semiconductor wafer in an anisotropic manner, resulting in deep grooves at uniform intervals from one another in the surface of the semiconductor wafer, the deep grooves being very narrow in comparison to the distances between neighboring grooves. The surface of the grooves as well as the surface of the semiconductor material between adjacent grooves can be either a p or n layer, and the material disposed immediately below the surface is material of an opposite conductivity type, that is, n or p conductive material, resulting in a pn-junction close to the surface of the semiconductor body. The semiconductor body and the pn-junction generated in this manner have a surface comparable to that of a ribbed profile plate. FIG. 1 of the aforementioned publication shows such a single crystal semiconductor body manufactured by means of anisotropic etching.